[IronDragon]

Personally I always give him the Flail of Ages and Daystar. If you are already wielding the Crom Faeyr +4 or will soon be wielding it I would stick with that and maces (mace of disruption or skullcrusher and hand over the FoA to Sola.

Some good alternatives:
Wyvern's Tail +2 - Victims must make a saving throw vs. poison or take 5 hit points of poison damage

Dragon Slayer - aside from doing double damage to dragons including:
Immunity to Fear, Regenerate 1 hit point every 10 rounds and Detect Invisible

Sword of Balduran - +10% to lore and +10% Magic Resistance.

Blade of Roses +3 - +2 Charisma

Celestial Fury - the best (pretty much only) katana, its ability to stun opponents is truly invaluable.

Providing Sola with proficiencies in bastard sword may be a good idea in the long run, SOA is criminally devoid of good bastard swords but there are two VERY good ones in ToB.